Exam 4 - Renal Flashcards
(303 cards)
1
Q
In to something
A
Afferent
2
Q
Out of something
A
Efferent
3
Q
PCT
A
Proximal convoluted tubule
4
Q
LOH
A
Loop of Henle
5
Q
DCT –
A
Distal convoluted tubule
6
Q
JGA –
A
Juxtaglomerular apparatus
7
Q
Functions of the Kidneys
HELPS TO…
A
HELPS TO…
1) Regulate blood ionic composition
2) Regulate blood pH
3) Regulate blood volume
4) Regulate blood pressure
5) Maintain blood osmolarity
6) Produce certain hormones
7) Regulate blood glucose levels
8) Excrete wastes and foreign substances
8
Q
Kidney Functions:
HELPS TO…
Regulate blood ionic composition by?
A
—Helps to regulate blood levels of ions like sodium (Na+), potassium (K+), calcium (Ca2+), chloride (Cl-), and phosphate (HPO42-)
9
Q
Kidney Functions:
HELPS TO…
Regulate blood pH by?
A
—Kidneys excrete variable amount of hydrogen ions (H+) into urine and conserve bicarbonate ions (HCO3-); bicarb is important buffer of H+
10
Q
Kidney Functions:
HELPS TO…
Regulate blood pressure by?
A
Kidneys excrete enzyme renin, this activates renin-angiotensin-aldosterone pathway; increased renin = increased blood pressure
11
Q
Kidney Functions:
HELPS TO…
Excrete wastes and foreign substances by?
A
By forming urine, kidneys help body to get rid of wastes
- –Ammonia and urea- from deamination of amino acids
- –Bilirubin- catabolism of hemoglobin
- –Creatinine- breakdown of creatine phosphate in muscle fibers
- –Uric acid- catabolism of nucleic acids
Foreign substances
- –From diet
- –Drugs
- –Environmental toxins
12
Q
Kidney Functions:
HELPS TO…
Maintain blood osmolarity by?
A
Separately regulates loss of water and loss of solutes in urine, kidneys maintain relatively constant osmolarity close to 300mOsm/liter
13
Q
Kidney Functions:
HELPS TO…
Produce certain hormones by?
A
Kidneys produce the hormones calcitriol (active form of Vitamin D) erythropoietin (stimulates production of RBC’s) and renin (hormone/enzyme)
14
Q
Kidney Functions:
HELPS TO…
Regulate blood glucose levels by?
A
Like the liver, the kidneys can use amino acid glutamine in gluconeogenesis, which can then release new glucose into the blood stream to help maintain normal level
15
Q
Right kidney is slightly lower than left – Why?
A
Liver
16
Q
Anatomy of Kidneys:
Located in ?
Anatomically between…
Partially protected by the?
A
retroperitoneal space
…last thoracic and 3rd lumbar vertebrae
11th and 12th ribs
17
Q
Anatomy of Kidneys:
Concave medial border (Hilum) faces the…
A
spinal column
18
Q
Anatomy of Kidneys:
_____ (Hilum) faces the spinal column
A
Concave medial border
19
Q
Anatomy of Kidneys:
_____ (Hilum) faces the spinal column
A
Concave medial border
20
Q
look at anatomy of kidneys and position of kidneys slides
A
well done
21
Q
External Anatomy of the Kidney:
Three External layers?
A
Renal fascia- Outermost layer
Dense connective tissue anchors kidney to surrounding structure and retroperitoneal wall
Adipose capsule- Middle layer
Fatty tissue surrounding renal capsule, protection and holds kidney in place in cavity (aka “renal fat pad”)
Renal capsule- Innermost layer
Smooth, transparent connective tissue covering that is continuous with ureters; helps maintain shape of kidney and offers protection
22
Q
External Anatomy of the Kidney:
Dense connective tissue anchors kidney to surrounding structure and retroperitoneal wall
A
Renal fascia- Outermost layer
23
Q
External Anatomy of the Kidney:
Fatty tissue surrounding renal capsule, protection and holds kidney in place in cavity (aka “renal fat pad”)
A
Adipose capsule- Middle layer
24
Q
External Anatomy of the Kidney:
Smooth, transparent connective tissue covering that is continuous with ureters; helps maintain shape of kidney and offers protection
A
Renal capsule- Innermost layer
25
External layers of the kidney, outermost to innermost:
Renal fascia- Outermost layer
Adipose capsule- Middle layer
Renal capsule- Innermost layer
26
External Anatomy of the kidney, outermost to innermost from PHOTO:
```
Pararenal fat
Renal Fascia
Perirenal fat
Renal Capsule
Kidney
```
27
Look at slide 18 on YOUR PPT... this pic is on the exam with a second order question of what does this feature do!
hemisection of kidney with half of photo elements circled
28
Internal Anatomy of the Kidney:
Cortex
Medulla
Pyramid
Papilla
Columns
Lobe
Minor calyx
Major calyx
Renal Pelvis
Renal sinuses
Renal hilum
29
Internal Anatomy of the Kidney:
Contains all of the glomeruli and convoluted tubules of nephrons
Also makes the columns that lay between pyramids
Cortex-
30
Internal Anatomy of the Kidney:
Contains all of the loops of Henle and collecting ducts
Collection of all renal pyramids comprise the medulla
Medulla
31
Internal Anatomy of the Kidney:
one portion of the medulla
8-18 per kidney
Pyramid
32
Internal Anatomy of the Kidney:
narrow apex of the pyramid
Contains the papillary duct leading to minor calyx
Papilla
33
Internal Anatomy of the Kidney:
space between renal pyramids
Is a portion of the renal cortex
Columns-
34
Internal Anatomy of the Kidney:
- a functional region within the kidney
Pyramid (medulla) + overlying cortex + ½ each adjacent column (cortex)
Lobe
35
Internal Anatomy of the Kidney:
- small chambers that collect urine directly from papilla
8-18 each kidney
Minor calyx
36
Internal Anatomy of the Kidney:
- larger chambers that collect urine from multiple minor calyces
2-3 each kidney, extensions of ureters
Major calyx
37
Internal Anatomy of the Kidney:
- major calyces drain into one large chamber (pelvis),
This mixes/collects all urine from entire kidney
Connects to the ureter outside of the kidney
Renal pelvis
38
Internal Anatomy of the Kidney:
The kidney is 3-dimensional, so in between the other structures there are spaces that house some adipose tissue, the blood vessels, and nerve supply
Renal sinuses
39
Internal Anatomy of the Kidney:
- a region
Indentation of kidney where ureter emerges with blood and lymphatic vessels, and nerves
Renal hilum
40
Renal blood supply:
Renal blood flow is ____ per minute and ___ mL per kidney
Total amount of blood in adult is 4500-5500mL
Starts at ___ level and then branches from there into smaller vessels
Specialized capillary called a _____ is involved in this flow
1200mL; 600mL per kidney
aortic
glomerulus
41
This glomerulus allows for filtration, but not....
reabsorption
Exits out of glomerulus, no entrance back into it!
42
Talk through the blood supply of the kidney in order through the entire system.... (16 total)
```
Aorta
Renal artery
Segmental artery
Interlobar artery
Arcuate artery
Interlobular artery (also called radial arteries)
Afferent arteriole
Glomerulus (modified capillary; tufted)
Efferent arteriole
Peritubular capillaries (both types of nephrons)
Vasa recta (juxtamedullary nephrons only)
Interlobular vein (also called radial veins)
Arcuate Vein
Interlobar Vein
Renal Vein
Inferior vena cavae
```
43
Blood flows into the kidney’s to get filtered
-It enters each corpuscle, gets filtered through the glomerulus, and exits the corpuscle to flow into a capillary system
-----Blood is filtered in the _____, where things can be removed only
-----When in the _____, blood will still act like it does in any other capillary in the body – stuff will move in and out of the capillaries depending on pressure
- This capillary action acts as a....
- ----Depending on the body’s needs, it can reabsorb/secrete more water/solutes as needed
glomerulus
peritubular capillaries/vasa recta
....secondary filter
44
Blood flows into the kidney’s to get filtered
As blood flows through, certain substances are removed from blood and placed into the urinary tubular system.... this is known as ?
This is known as filtrate
45
Filtrate is first found in the.....
From there is flows through the tubules and then into _____
While in these ducts, things can still be added to it, or removed from it
glomerular capsule (Bowman’s capsule)
collecting ducts
46
Once the filtrate leaves the collecting duct, it is then called _____
urine
47
Functional unit of the kidney –approximately 1,000,000 in each kidney
nephron
48
Nephron consists of two parts:
Renal Corpuscle
Renal Tubule
49
- where blood is filtered (two parts)
Renal Corpuscle with two parts
1) Glomerulus
2) Glomerular capsule (aka Bowman’s capsule)
50
- filtered contents (from blood; three parts)
Renal Tubule (three parts as follows):
Proximal Convoluted tubule (PCT)- attached to capsule
Loop of Henle (nephron loop)- middle section
Distal Convoluted tubule (DCT)- distant from capsule, empty into collecting duct
51
three parts of renal tubule (filtered contents)
PCT
LOH
DCT
52
Corpuscle and both convoluted tubules reside in ____
cortex
53
Only Loop of Henle extends into the...
renal medulla
54
Two Different types of nephrons?
Cortical nephron
| Juxtamedullary nephron
55
– 85% of nephrons
- ----Renal corpuscles lie in outer portion of renal cortex
- ----Short loops of Henle (Just barely reach into outer region of medulla)
- ----Peritubular capillaries only
Cortical nephron
56
– 15% of nephrons
- ----Renal corpuscles lie deep in the renal cortex
- ----Long loops of Henle (Reach deep into medulla)
- ----Peritubular capillaries that give rise to the Vasa recta (Vasa recta: capillary bed that extends into medulla surrounding the Loop of Henle)
Juxtamedullary nephron
57
cortical nephrons have ___ capillaries only
peritubular capillaries only
58
which nephron has short LOH?
Cortical nephron
59
which nephron has long LOH?
Juxtamedullary nephron
60
which nephron has Peritubular capillaries that give rise to the Vasa recta ?
Juxtamedullary nephron
61
capillary bed that extends into medulla surrounding the Loop of Henle
Vasa recta
62
Cortical nephrons:
Short nephrons
_______ lie in the outermost portion of the cortex
Descending limb of loop of Henle barely dips into the ____
After a hairpin turn, the ascending limb of the Loop of Henle ____
Renal corpuscles
renal medulla
returns to the cortex
63
Cortical nephrons:
Peritubular capillaries
Arise from the _____
Intermingle throughout the ____
These then flow into _____ and eventually back into systemic circulation
efferent arteriole
proximal and convoluted tubules
interlobular veins
64
Juxtamedullary Nephrons:
Long nephrons
---Renal corpuscles lie in the cortex
---Descending limb of loop of Henle dives deep into the ___ (which the longer descending loop means what?)
---After a hairpin turn, the ascending limb of the Loop of Henle climbs back to the cortex
renal medulla (Anatomy lends to very dilute and/or concentrated urine)
65
Juxtamedullary Nephrons:
Peritubular capillaries
Arise from the efferent arteriole
Intermingle throughout the proximal and convoluted tubules
In the juxtamedullary nephrons only, a _____ exists coming off of these peritubular capillaries
specialized capillary system
66
Juxtamedullary Nephrons:
Vasa Recta
Coming from the peritubular capillaries, this type of capillary system dives deep into the renal medulla
Flows side by side each of the loops of Henle so that things can.....
....Flow out of the capillaries and into the filtrate as well as
Out of the filtrate and into the capillaries
67
The design with the use of vasa recta is extremely important for keeping a...
constant osmotic (pressure) gradient so that things can flow in and out
68
short, wide afferent arteriole =
low-resistance input pathway
69
efferent arteriole plus vasa recta =
high-resistance outflow pathway
70
flow is controlled by vasoconstriction of which arteriole?
afferent arteriole
71
The arteriole coming into the corpuscle/glomerulus
Brings blood in for filtration
Wider lumen, thicker walls
Has much more capability to constrict or dilate when compared to efferent arteriole
Afferent arteriole
72
This arteriole has much more capability to constrict or dilate when compared to the other...
afferent arteriole
73
Ball of twine-like capillary structure that buds off of the afferent arteriole
Glomerulus
74
Glomerulus
Modified simple squamous epithelial cells called
podocytes
75
Podocytes have fingerlike projections _____ that wrap around the glomerular capillaries
(pedicels)
76
The arteriole leaving the corpuscle/glomerulus
Efferent arteriole
77
Brings blood with larger solutes (i.e. proteins) into the peritubular capillaries (or vasa recta) and then back into systemic circulation
Efferent arteriole
78
Smaller lumen size, thinner walls
Smaller lumen size aids in back-pressure sometimes needed for glomerular filtration (continued later in lecture)
Efferent arteriole
79
PCT/LOH/DCT/Collecting Duct
Together comprise?
Tubule System
80
A single layer of epithelial cells forms the entire wall of the....
glomerular capsule, renal tubule, and ducts
Each section of cells has minor differences that allow for different functions
81
Simple cuboidal epithelial cells with prominent microvilli brush-border facing lumen (apical surface)
Microvilli increase surface area for absorption and secretion
PCT- proximal convoluted tubule
82
(LOH) Loop of Henle (thin descending and thin ascending limb portions)
Histology?
Simple squamous epithelial cells
83
(LOH) Loop of Henle (thick ascending limb portion)
Histology?
Simple cuboidal to low columnar epithelial cells
84
DCT- distal convoluted tubule
Histology wise...
Most of DCT – ?
Last part of DCT- ?
Most of DCT – simple cuboidal epithelial cells
| Last part of DCT- simple cuboidal epithelial cells that contain
85
In the DCT...
- receptors for ADH and aldosterone
Principal cells
86
In the DCT...
- help play a role in blood pH
Intercalated cells
87
Collecting Duct
| Simple cuboidal epithelial cells that also contain:
Principal cells- receptors for ADH and aldosterone
Intercalated cells- help play a role in blood pH
88
Last part of DCT- simple cuboidal epithelial cells that contain:
Principal cells- receptors for ADH and aldosterone
| Intercalated cells- help play a role in blood pH
89
The fluid that enters the afferent arteriole and into the glomerulus
The fluid that gets “filtered” in the glomerulus
Blood/Serum
90
The leftover blood/serum and components not filtered into the glomerular capsule, leave the corpuscle via the
efferent arteriole
91
The fluid/solutes that were filtered out of blood at the glomerulus
The fluid/solutes that enters the renal tubular system at the glomerular capsule
Fluid/solutes can still be reabsorbed/secreted over and over again
Filtrate
92
Once the filtrate leaves the collecting ducts, it is now called “urine”
Urine
93
Nephrons and Collecting ducts perform three functions:
1) glomerular filatration
2) tubular reabsorption
3) tubular secretion
94
water and many solutes found in blood move across the wall of the glomerulus, into the glomerular capsule (Bowman’s capsule) and into tubules
Glomerular filtration:
95
water and solutes that are now flowing through the tubule system can get reabsorbed (~99% of filtrate is reabsorbed back into bloodstream)
Tubular reabsorption:
96
due to the peritubular capillaries and vasa recta, there is still the chance to dump unwanted materials into the filtrate such as wastes, drugs, excess ions
Tubular secretion:
97
once out of the collecting duct, there is no more opportunity for exchange; expelling waste matter
Excretion:
98
Garbage trucks dump smaller garbage (potential recyclables) into a mechanism that can sort out recyclables
Glomerular filtration
99
```
Large items (such as appliances) are left on the truck to be taken elsewhere
Proteins/RBC’s that cannot make it through the filtration membrane
```
Still in blood, exits glomerulus via efferent arteriole
100
Smaller refuse is placed onto a conveyor belt where workers separate the useful components (cans, plastic, glass)
Reabsorption of useful products (while in tubule system)
101
The unusable refuse is thrown back into the garbage truck to be sent to the landfill
Wastes are secreted back into the ducts (filtrate) to be made into urine and excreted
102
The amount that makes it into the glomerular capsule space and tubule system
Glomerular Filtration
103
Adults create 150-180 liters of filtrate a day
true
104
99% is usually reabsorbed and returned to circulation
Glomerular Filtration
105
Glomerular Filtration 99% reabsorbed.... Leaving only...
1-2 liters of urine produced a day
106
Filtration Membrane
Glomerular capillaries and podocytes form a “leaky” barrier in the capsule
Loosely packed- allows water and certain solutes to pass into capsular space
Prevents most plasma proteins, blood cells, platelets from getting into capsular space
107
Filtration Membrane
Glomerular ___ and ____ form a “leaky” barrier in the capsule
capillaries and podocytes
108
Filtration Membrane Consists of three layers of filtration:
Filtration Membrane Consists of three layers of filtration:
1) Fenestrations of endothelial cells (inner most layer of capillary)
- ---Prevents blood cells from passing, but allows all other components of blood plasma through
2) Basement membrane/Basal lamina (middle layer of capillary)
- ---Prevents large proteins from passing through
3) Slit membranes between pedicels (podocyte arms; outer most layer of capillary)
- ---Prevents filtration of most other proteins
109
Interspersed throughout the glomerular capillaries
Regulate surface area available for filtration
Mesangial Cells and Filtration Membrane
110
Mesangial Cells and Filtration Membrane:
Regulate surface area available for filtration
When relaxed, _____
When contracted, _______
surface area is maximal
reduced area available
111
when mesangial cells are relaxed surface area...
is maximal
112
when mesangial cells are contracted surface area...
reduced area available
113
Glomerular Filtration Pressure
Although still capillaries, pressure is higher in these than in any other capillaries in the body
Larger surface area
Larger fenestrations for easier filtration
Efferent arteriole is smaller than the afferent
114
Efferent arteriole is smaller than the afferent
This then requires more pressure to get plasma...
This pressure builds backwards into the glomerulus...
...OUT of the glomerulus through the efferent arteriole
...increasing filter pressure (positive pressure)
115
Pressure in glomerulus pushing outward into capsular space
Usually 55mmHg
Glomerular blood hydrostatic pressure (GBHP)
116
Hydrostatic pressure exerted by the fluid in capsular space that pushes inward on the visceral glomerular membrane
“back pressure”
Usually 15mmHg
Capsular hydrostatic pressure (CHP)
117
Pressure due to proteins in blood plasma (mainly albumin)
Opposes filtration (Pulls on fluid/solutes to keep them in the glomerulus if possible)
Usually 30mmHg
Blood colloid osmotic pressure (BCOP)
118
Net Filtration Pressure / NFP is the pressure that is supposed to
PROMOTE filtration
119
NFP = ?
in healthy kidneys about how many mmHg?
NFP= GBHP-CHP-BCOP
NFP= 55mmHg-15mmHg-30mmHg
10mmHg – normal NFP in healthy kidneys
120
As long as the NFP is a positive number,
filtration will occur
121
If NFP calculates into a negative number,
NO FILTRATION is occurring
122
Promoting filtration eventually leads to
urine production
123
the amount of blood filtered by the kidneys’ glomeruli into capsular space per unit time
GFR
124
average adult GFR
125mL/min in average adult
125
Homeostasis of body fluids requires a _____ GFR
near constant
126
If GFR too fast-
filtrate may pass too quickly and required substances may not be reabsorbed
127
If GFR too slow-
nearly all filtrate may be reabsorbed and certain wastes may not be excreted efficiently
128
CALCULATING GFR
An “estimated” rate only as it involves calculations and not actual measurements
```
Calculated using the serum creatinine levels and some or all of the following:
Age
Race
Weight
Gender
```
129
- waste from the breakdown of muscle (normal)
Creatinine
130
As blood is filtered through the nephrons, the kidney neither reabsorbs or metabolizes this substance
Creatinine
131
Should freely pass through the filtration membrane and be urinated out
Creatinine
132
In a normal healthy adult, the serum level should be near or at the same level of the urine creatinine clearance (24hour urine collection)
IF URINE LEVEL LOW?
CAUSING INCREASED SERUM OF WHAT?
If the urine level is low, this means the kidneys are not filtering the serum creatinine properly (kidney damage)
Usually means that the serum level will be elevated
133
In calculating the estimated GFR, many studies found that the African American population (especially Afro-Caribbean Black patients) had a much higher serum creatinine (SCr) level
Generally have increased muscle mass
Generally have higher rates of muscle breakdown
134
When accounting for this shift of normal levels, it shows that the average African American patient will have a “higher normal” GFR
21% above the normal levels for non-black patients
135
GFR directly related to pressures that determine net filtration pressure
Ex: Severe blood loss reduces mean arterial pressure as well as glomerular blood hydrostatic pressure
If GBHP drops by even 10mmHg, filtration in the glomerulus stops (remember the NFP is what is needed to force filtration)
136
If GBHP drops by even 10mmHg, filtration in the glomerulus....
....stops (remember the NFP is what is needed to force filtration)
137
Mechanisms that regulate GFR?
1) Renal autoregulation
- --Innate actions that occur within the kidney
2) Neural regulation
- --Sympathetic nervous system input (or reduction of input)
3) Hormonal regulation
- --Angiotensin II
- --Atrial natriuretic peptide (ANP)
138
Mechanisms that regulate GFR
Renal autoregulation?
Innate actions that occur within the kidney
139
Mechanisms that regulate GFR
Neural regulation?
Sympathetic nervous system input (or reduction of input)
140
Mechanisms that regulate GFR
Hormonal regulation?
Angiotensin II
| Atrial natriuretic peptide (ANP)
141
GFR- Renal Autoregulation
Kidney’s help maintain their own GFR by two mechanisms:
1. Myogenic mechanism
| 2. Tubuloglomerular feedback
142
Myogenic Mechanism
immediate increase in BP causes?
which can cause?
Immediate increase in BP
causes
Myogenic vasoconstriction
which can cause
Compensatory vasodilation
143
increased BP (as in exercise) causes stretching of afferent arteriole, this causes smooth muscle contraction of afferent arteriole, reduces renal blood flow, which reduces GFR
Myogenic mechanism-
144
This helps to preserve nephron integrity with increased blood pressure
When threat of increased BP is reduced, afferent arteriole may vasodilate to increase GFR to balance out the system
Myogenic mechanism-
145
the Juxtaglomerular apparatus (JGA; see following slides for full explanation)
Tubuloglomerular feedback
146
When GFR increases, rate through the tubules increase
Reabsorption of Na+, Cl- and water reduce due to rate of flow
Macula densa cells sense the increased levels of these in filtrate
These levels inhibit the release of nitric oxide (NO; vasodilator)
If NO inhibited, afferent arterioles constrict, lowers GFR
Lowered GFR slows rate through tubules
Tubuloglomerular feedback-the Juxtaglomerular apparatus (JGA)
147
Tubuloglomerular feedback-the Juxtaglomerular apparatus (JGA)
When GFR increases, rate through the tubules increase
Reabsorption of Na+, Cl- and water reduce due to rate of flow
Macula densa cells sense the increased levels of these in filtrate
These levels inhibit the release of nitric oxide (NO; vasodilator)
If NO inhibited, afferent arterioles constrict, lowers GFR
Lowered GFR slows rate through tubules
148
A complex structure that has the ability to affect systemic blood pressure through the autoregulation of tubuloglomerular feedback
Juxtaglomerular Apparatus (JGA)
149
There is one JGA for every _____
nephron
150
Juxtaglomerular Apparatus (JGA) contains....
Juxtaglomerular cells
---Found in the walls of the afferent arteriole
Macula densa cells
---Found in the walls of the distal convoluted tubule
```
Lacis cells (modified mesangial cells)
---Located between afferent arteriole, efferent arteriole, and DCT
```
151
---Found in the walls of the afferent arteriole
| efferent arteriole, and DCT
Juxtaglomerular Apparatus (JGA) Cells including...
Juxtaglomerular cells (AA)
Macula Densa Cells (DCT)
Lacis Cells (Modified Mesangial Cells / Extraglomerular)
152
---Found in the walls of the distal convoluted tubule
Macula densa cells
153
---Located between afferent arteriole, efferent arteriole, and DCT
Lacis cells (modified mesangial cells) AKA extraglomerular mesangial cells
154
The afferent arterioles contain
juxtaglomerular cells
155
Modified smooth muscle cells that have two functions:
1. Detect when blood pressure is too low (by sensing the lack of stretch of the afferent arteriole wall)
2. They synthesize, store, then secrete hormone/enzyme Renin (described later in RAAS)
- ----Renin causes a cascade of events that helps to increase blood pressure when needed
156
The distal convoluted tubule (where it meets the afferent arteriole) contains
macula densa cells
157
macula densa cells
Closely packed specialized cells that have two functions
1. Detect increase in NaCl (Sodium Chloride) concentrations in the filtrate
2. In response to this concentration check, these cells release
ATP, Adenosine in various concentrations which act locally
----These trigger contraction of afferent arteriole
----This causes GFR to reduce, which reduces the rate tubule flow
158
In response to this concentration check, these cells release ATP and Adenosine in various concentrations which act locally to do these two things...
macula densa cells which...
- ---These trigger contraction of afferent arteriole
- ---This causes GFR to reduce, which reduces the rate tubule flow
159
located in between the afferent, efferent and distal convoluted tubule junction
Lacis Cells (Modified Mesangial cells)
160
Contract or relax to make small regulatory changes in response to the signals that the other JGA cells are sending
Lacis Cells (Modified Mesangial cells)
161
Together the macula densa, juxtaglomerular cells, and Lacis cells make the
Juxtaglomerular Apparatus
162
tubuloglomerular feedback
Depending on the filtrate analysis at this location, the filtration performance of the glomerulus can be changed
Helps regulate blood pressure within the kidneys
-----This can eventually effect systemic blood pressure
163
Blood vessels of the kidney are supplied by
sympathetic nervous system fibers only
164
At rest, sympathetic stimulation is low:
Afferent and efferent arterioles are ___
Blood flow into and out of the glomerulus is _____
Afferent and efferent arterioles are dilated
Blood flow into and out of the glomerulus is relatively equal
165
With greater sympathetic stimulation (exercise, fight/flight)
_____ of the afferent arteriole occurs
Blood flow ____ into glomerulus
GFR __________
Vasoconstriction of the afferent arteriole occurs
Blood flow decreases into glomerulus
GFR decreases
166
This decreases because during sympathetic stimulation we need blood elsewhere in the body...
This also protects the nephrons from the rapid rise in blood pressure
GFR decreases
167
two hormones that control regulation of GFR?
Angiotensin II- reduces GFR
- --Very potent vasoconstrictor
- --Mostly acts on efferent arterioles
- --Reduces renal blood flow
Atrial natriuretic peptide (ANP)- increases GFR
- --Secreted by the atria (heart)
- --Usually secreted in response to increase in volume
- --Markedly vasodilates afferent and efferent arterioles
- --GFR increases
168
Passive movement occurs when pressure gradients allow flow of something from a high concentration to a low concentration; it does not require ATP energy to occur
Example in kidneys?
Example: Glomerular filtration occurs from pressures alone, not from ATP expenditure
169
Active movement occurs usually against the concentration gradient and with the help of ATP expenditure
Ex in kidneys?
Example: Sodium/Potassium pumps (Na+/K+) expend energy converting ATP to ADP
170
Tubular Reabsorption
Normally 99% of filtrate is reabsorbed
Epithelial cells all along the renal tubule and ducts reabsorb, but the ____ cells make the largest contribution to reabsorption
Solutes that are both actively and passively reabsorbed include....
PCT
Glucose, amino acids, urea, sodium, potassium, calcium, chloride, magnesium, bicarbonate, and phosphates
171
Solutes that are both actively and passively reabsorbed include....
```
Glucose,
amino acids,
urea, sodium,
potassium,
calcium,
chloride,
magnesium,
bicarbonate, and
phosphates
```
172
Once fluid passes through the PCT, cells located more distally “fine tune” the reabsorption process.... where does this occur?
Loop of Henle, DCT, Collecting duct
173
If small proteins and peptides are passed through the glomerular filter....
They are usually reabsorbed by pinocytosis
174
Reabsorption can occur by
Paracellular reabsorption
| Transcellular reabsorption
175
Reabsorption between adjacent tubule cells
Passive movement only
Thought to account for up to 50% of reabsorption
Paracellular reabsorption
176
Reabsorption - through the tubule cell itself
Passive and Active movement
Transcellular reabsorption
177
- the lumen side of the cell
Apical membrane
178
- the interstitial side of the cell
Basolateral membrane
179
look at image of transcellular vs paracellular reabsorption from the slides
good job hero
180
Water follows solutes almost always and
Solute reabsorption drives water reabsorption via ____
This is called ____
osmosis
obligatory water reabsorption
181
obligatory water reabsorption
90% of actual water reabsorption by the kidneys occurs with the reabsorption of
Sodium (Na+)
Chloride (Cl-)
Glucose
182
Obligatory Water Reabsorption occurs in
the PCT and the descending limb of the loop of Henle
183
These segments are always permeable to water
the PCT and the descending limb of the loop of Henle
184
After obligatory water reabsorption.... Reabsorption of the remaining 10% of water occurs by?
facultative water reabsorption
185
Regulated by ADH
Occurs in the late DCT and collecting ducts
facultative water reabsorption
186
facultative water reabsorption occurs in the ?
late DCT and collecting ducts
187
The transfer of materials from the capillaries (peritubular and/or vasa recta), interstitial spaces and tubule cells into the filtrate
Tubular Secretion
188
Tubular Secretion
Secreted substances include (but not limited to)
Hydrogen ions
----Secretion of hydrogen ions helps to control the blood pH
Potassium
Ammonium ions
Creatinine
Certain drugs like penicillin
189
Remember…the general idea is to make the concentration and the net-charge of solutes and water the same
This never actually occurs though because
There is a constant turnover of new blood coming into the kidney’s
The body signals the need for certain elements to be reabsorbed or secreted based on an attempt for homeostasis
190
there is constant movement of things across these membranes (tubule cell : interstitial fluid : capillary)...this constant movement generates
This constant movement generates an osmotic gradient as well as an electric gradient (+/-)
191
___ is a nitrogenous waste created when proteins are catabolized (broken down)
Ammonia
192
This is a very toxic substance and if left to accumulate in this form, it would be deadly
Ammonia
193
Much of the ammonia made in the body is circulated to the ____ (where it is converted to urea) or is excreted in urine
liver
194
is much less toxic than ammonia, but can still be deadly if left to accumulate
Urea
195
Urea plays a significant role in creating and maintaining the
osmotic gradient in the renal medulla
196
This “safeguards” the body’s supply of an important buffer
Most of the bicarb (HCO3-) is reabsorbed in the PCT
197
where is bicarb reabsorbed
PCT
198
Bicarb cannot be reabsorbed in complete form, has to be “processed” to be reabsorbed
When H+ is secreted into lumen of the tubule in the PCT, the HCO3- reacts with it to form H2CO3 (carbonic acid)
This then dissociates into CO2 and H2O
CO2 diffuses into the tubule cells and joins with H2O already in the cell to form H2CO3
This H2CO3 then dissociates into H+ and HCO3-
199
For every H+ secreted into tubular lumen, _______ are reabsorbed
one HCO3- and one Na+
200
Largest amount of solute and water reabsorption from filtered fluid occurs in the
Proximal Convoluted Tubule - PCT
201
100% of glucose, amino acids, vitamins
| and 90% of bicarb are reabsorped here
PCT
202
Sodium (Na+) is actively transported out of tubule and into interstitial fluid.... what is co-transported?
Glucose and amino acids are co-transported with Na+
203
As Na+ moves into blood, this creates a significantly positive environment in blood causing....
Chloride (Cl-) ions passively move from filtrate into interstitial fluid to help balance this
204
Here Urea passively moves out of tubule
PCT
205
Bicarb is reabsorbed here
PCT
206
Movement of ______ into interstitium creates a significant osmotic imbalance now, so water is obligated to move out of filtrate and into interstitum by osmosis
Na+ and Cl-
207
Cells lining the PCT and the descending LOH are especially permeable to water because of the presence of
aquaporin-1 channels
208
These are protein water channels that increase the rate of water movement
aquaporin-1 channels
209
The osmosis of water will often bring K+ and Ca++ with it in a motion called
solvent drag
210
solvent drag
The osmosis of water will often bring K+ and Ca++
211
Multiple functions of PTH
PTH stimulates cells in the PCT to secrete phosphate
PTH stimulates calcitriol (Vitamin D) to be made in PCT cells and then be absorbed into blood
----Calcitriol circulates to intestines where it causes more calcium from digestive system to be absorbed
PTH also stimulates cells in the DCT to reabsorb more calcium
212
PTH stimulates cells in the PCT to secrete
phosphate
213
PTH stimulates calcitriol (Vitamin D) to be made in...
PCT cells and then be absorbed into blood
214
PTH also stimulates cells in the ____ to reabsorb more calcium
DCT
215
In the entire LOH, unlike the PCT, solute and water reabsorption are
independently regulated
216
15% of water left
(in descending portion only, none in the ascending portion)
217
mostly water reabsorption and solute secretion (concentrates the filtrate)
Descending limb
218
no water reabsorption, but reabsorption of solutes occurs (dilutes the filtrate)
Ascending limb
219
This region is passively permeable to water and solutes
Descending Limb LoH
220
Solute reabsorption occurring simultaneously in the _____ creates a higher concentration (osmolarity) in the interstitial fluid
ascending limb
221
Descending Limb LoH
increased interstitial fluid osmolarity (from ascending limb) forces the descending limb to attempt to find equilibrium causing....
Causes water reabsorption and solute secretion to occur in the descending limb
Urea, Na+, and Cl- are secreted into tubule
222
Descending Limb LoH
More solutes and less water causes the “first” concentration of filtrate inside the tubule (hyperosmotic)
Descending Limb LoH
223
Ascending Limb LoH
This region is passively permeable to small solutes, but impermeable to water (no water reabsorption occurs here)
Thin portion
224
Active reabsorption (movement out of tubule) of Na+, K+, Cl- occurs here, but this region is still impermeable to water
Thick portion
225
This means that as filtrate moves up the ascending limb, it dilutes even more
Active reabsorption (movement out of tubule) of Na+, K+, Cl- occurs here, but this region is still impermeable to water
226
Early portion of the DCT
| very little Na and Cl are left and only 10-15% of water... but at the late portion of DCT
By the time filtrate reaches this portion, 90-95% of filtered solutes/water have been reabsorbed and returned to interstitium/bloodstream
227
Specialized cells found intermixed in the DCT and throughout the collecting ducts
Principal cells
| Intercalated cells
228
In the DCT and collecting ducts, the amount of reabsorption of solutes/water is dependent on feedback from the body in general
Hormonal (ADH, Aldosterone, Atrial Natriuretic Peptide)
Osmoreceptors throughout the body (ex: body requires more sodium than what’s already been reabsorbed)
229
DCT is similar to PCT in that Na+ reabsorption occurs via
active transport
230
In DCT/Collecting ducts though, the cells are relatively still impermeable to water, so...
BUT… when the need arises, there is a mechanism that gets activated in these cells that allows them to be able to ____
...water does not follow Na+ via osmosis
selectively reabsorb water
231
______ causes principal cells in the DCT and collecting ducts to become permeable to water
Anti-Diuretic Hormone (ADH)
232
ADH targets ____ in the DCT and collecting ducts
principal cells
233
Antidiuretic Hormone (ADH)
Triggers these cells to generate ____ in the apical membrane of the cells lining the tubule
aquaporin-2 channels
The presence of these TEMPORARY channels allows the tubule wall to become more permeable to water via osmosis
234
Antidiuretic Hormone (ADH)
The more ADH that is present, the more
aquaporin-2 channels will be generated
235
Antidiuretic Hormone (ADH)
In general, in the presence of ADH, we produce a small quantity of....
highly concentrated urine
236
ADH triggers aquaporin 2 channels in the....
apical membrane of the cells lining the tubule
237
Incidentally, in the presence of ADH, when more water is reabsorbed, it creates an osmotic imbalance when it gets to the...
distal collecting duct
238
osmotic imbalance from ADH forces ___ to be reabsorbed
urea
239
The addition of urea in the interstitial fluid from the collecting duct assists in increasing the high osmolarity in the interstitial fluid
This helps to keep the osmotic gradient constantly moving
The urea that is reabsorbed at the distal collecting ducts migrates through interstitial fluid and gets secreted in the descending limb of the loop of Henle (Urea recycling)
240
When ADH is at it maximal secretion
Body can produce as little as 400-500mL of very concentrated urine each day
The rest is returned to the interstitium/blood stream instead of being urinated out
241
When blood pressure/volume stabilizes
ADH levels decline causing
The aquaporin-2 molecules to be removed from principal cells
Normal volume of normal to dilute urine produced
242
Aquaporin-2 molecules are only effective in the presence of ADH whereas aquaporin-1 molecules are....
...independently functioning in the PCT/LOH
243
Under the influence of aldosterone, principal cells cause the following:
Sodium reabsorption (usually brings water with it)
Potassium secretion
244
What causes aldosterone to be released?
Hyperkalemia
Presence of angiotensin II
---This occurs when the renin-angiotensin-aldosterone system is stimulated by low blood volume or pressure
245
The principal cells are responsible for...
secretion of K+ and reabsorption of Na+
246
Look at Principal cells graphic!
DO it
247
intercalated cells are stimulated by
various osmoreceptor readings in reference to pH and potassium levels
248
intercalated cells are stimulated by
various osmoreceptor readings in reference to pH and potassium levels
249
Causes secretion of hydrogen (H+) ions
Causes reabsorption of bicarb
Causes reabsorption of potassium (K+)
Type A Intercalated Cells
250
Causes reabsorption of hydrogen (H+) ions
Causes secretion of bicarb
Causes secretion of potassium (K+)
Type B Intercalated Cells
251
When ANP is stimulated, it has direct actions on the cells located in the
DCT and the Collecting Ducts
252
Inhibits the reabsorption of sodium and water
Also inhibits the renin-angiotensin-aldosterone system
Atrial Natriuretic Peptide
253
Activated in response to low renal vascular flow/pressure
Renin-Angiotensin-Aldosterone System
254
System activated when blood volume/pressure is too low, no longer stretching the walls of the afferent arteriole
Renin-Angiotensin-Aldosterone System
255
This causes the _______ to secrete the hormone/enzyme renin into the blood stream
At the same time, angiotensinogen is released by hepatocytes into the blood
juxtaglomerular cells
256
secrete renin
juxtaglomerular cells
257
Renin finds angiotensinogen and cleaves off a 10-amino acid peptide
This converts angiotensinogen to angiotensin-1
258
is the active form of the hormone
Angiotensin II
259
Angiotensin I continues to course through the blood until it reaches the lungs
Here, angiotensin-I is converted to angiotensin-II by
lung endothelial angiotensin converting enzyme (ACE)
260
Angiotensin II affects renal physiology in three ways:
Decreases GFR by causing vasoconstriction of afferent arteriole
Enhances Na+, Cl- and water reabsorption in the PCT
Stimulates the adrenal cortex to release aldosterone
261
Aldosterone stimulates the principal cells in the collecting ducts to reabsorb more ___ and secrete more ____
Na+ and Cl- and secrete more K+
262
With increased reabsorption of Na+ and Cl-, more water is reabsorbed which causes INCREASED blood volume and blood pressure
duh... thanks raas
263
Body fluid volume homeostasis largely dependent on rate of water excretion in urine
When water intake is high, kidneys produce large amount of dilute urine
When water intake is low, kidneys produce a small amount of concentrated urine
264
The regulation of plasma osmolarity and volume are the responsibility of....
the Loop of Henle, the DCT, and the collecting ducts
265
```
Concentrating urine (initially)
----Permeable to water mostly, therefore concentrating the filtrate
```
Descending limb of LOH
266
```
Diluting urine (initially)
----Impermeable to water, therefore diluting the filtrate
```
Thick ascending limb of LOH
267
Where final dilution/concentration occurs
| Where the majority of ADH has its action
DCT + Collecting Ducts
268
In absence of ADH
Urine is diluted
269
In presence of ADH
Urine is concentrated
270
Dilution/Concentration in the DCT and the collecting ducts is controlled by the presence or absence of
ADH
271
Dilution/Concentration in the ___ and ___ is controlled by the presence or absence of ADH
DCT and the collecting ducts
272
Urinalysis metrics:
Volume- 1-2 liters in 24 hour period (24 hr urine collection)
Color- yellow or amber, varies with urine concentration and diet (beets, medications [pyridium], kidney stones can cause blood in urine)
Turbidity- transparent when voided, becomes cloudy with time
Odor- mildly aromatic, becomes ammonia-like with time
Bacteria turning urea back into ammonia
pH- ranges from 4.6-8.0, average is 6.0, varies with diet, high protein increases acidity, vegetarian increases alkalinity
Specific gravity- density (ratio of weight of solutes vs water) usually 1.001-1.035 (the higher the solutes the higher the value)
273
normal urine is protein free
true
274
Urea (from breakdown of proteins)
Creatinine (from breakdown of creatine phosphate in muscle)
Uric Acid (breakdown of nucleic acids)
Urobilinogen (breakdown of hemoglobin)
Small amount of fatty acids, pigments, enzymes, and hormones
Water accounts for 95% of urine
275
Two blood tests can provide kidney function information
Blood Urea Nitrogen (BUN)- measures urea (uremia)
Plasma creatinine- catabolism of creatine phosphate in skeletal muscle
276
This urea results from the catabolism and deamination of amino acids (proteins) in the liver
Urea can be reabsorbed from filtrate to help create/maintain an osmotic gradient in the kidneys
When GFR reduces severely (as in renal disease), BUN increases
A normal BUN level is 7-20mg/dL
Blood Urea Nitrogen (BUN)- measures urea (uremia)
277
Normally remains steady as the rate of creatinine excretion in urine equals its discharge from muscle
There is NO use for creatinine in the body, so we should excrete much, if not all of it in the urine
A normal SERUM creatinine level is anything below 1.6mg/dL
Plasma creatinine- catabolism of creatine phosphate in skeletal muscle
278
The volume of plasma (mL) that can be completely cleared of a substance per unit time (min)
For example the clearance of glucose is normally zero because normally 100% of glucose is reabsorbed, nothing gets excreted
If a drug is being administered (like penicillin) that has a high clearance (excreted in high doses in the urine) then the dosing of the medication must be high to be effective
279
plant polysaccharide, easily passes through the filter and is excreted in urine 100%
Inulin
Great measure of true GFR
280
Inulin is administered by IV continuously while concentration of plasma and urine inulin are measured along with urine flow rate
Great method but inulin is not produced in the body so this test is difficult to do
281
As creatinine is filtered, not reabsorbed, its clearance is a good estimate of GFR
At times, can overestimate GFR by 10-20%
Lab values needed: 24 hr urine volume (convert mL/day to mL/min), plasma and urinary concentration of creatinine (convert to mg/mL)
282
Urine Transportation, Storage, and Elimination route....
Collecting ducts –-papilla - papillary ducts - minor calyces – major calyces – renal pelvis – ureters – urinary bladder – urethra – toilet
283
Urine transport by peristalsis (renal pelvis to urinary bladder) aided by
hydrostatic pressure and gravity
284
Ureter - Pass obliquely into _____ aspect of bladder
posterior/inferior
285
Ureter Anatomy
Although no valve is present, a physiologic valve exists
When the bladder fills with urine, it pulls the bladder down which closes these valves so no “backflow” occurs
Called the anti-reflux mechanism
286
anti-reflux mechanism
When the bladder fills with urine, it pulls the bladder down which closes these valves so no “backflow” occurs
287
External urethral sphincter
Skeletal muscle (composed of deep perineal muscles/pelvic floor)
Voluntary
Sits just below the prostate (in males)
Is at the opening of the external urethral orifice (in females)
288
Prostatic
Membranous
Spongy
Male Urethra
289
circular smooth muscle forms internal urethral sphincter
Prostatic:
290
Contains:
Duct that transports prostatic fluids
Duct that transports sperm
Prostatic urethra
291
shortest region passing through urogenital diaphragm, circular skeletal muscle forms external urethral sphincter
Membranous urethra (Intermiediate)
292
longest region passing through penis
Spongy urethra
293
Spongy Urethra contains openings of
Bulbourethral (Cowper’s gland)-delivers alkaline fluid to help neutralize acidity of urethra
294
Female urethra is _____ to pubic symphysis, runs inferior/anterior from the _____ to the ____
Posterior
bladder neck and to the vaginal vestibule
295
located between clitoris and vaginal orifice
Female Urethra
296
female urethra think
musocas
| muscularis
297
consists of epithelium and lamina propria of female urethra
Mucosa of female urethra
298
Transitional epithelium near bladder; middle section is stratified or pseudostratified columnar; near external urethral orifice is nonkeratinized, stratified squamous
Mucosa of female urethra
299
circular, smooth muscle of female urethra
Muscularis:
300
Parasympathetic reflex initiates the mechanism for urination (micturition) which causes
Involuntary contractions of the detrusor muscle
Internal urethral sphincter to open
This causes urine to move from the bladder into the urethra
This causes the sensation that we perceive as our body telling us we need to urinate soon
Micturition
301
Micturition causes Involuntary contractions of the
detrusor muscle
302
After micturition.... Then, voluntary contraction of the external urethral sphincter helps to prevent urination until the appropriate time
Voluntary relaxation of this sphincter allows the flow of urine to occur
303
What are the two types of mesangial cells?
Intraglomerular vs Extraglomerular
Intraglomerular Mesangial Cells are inbetween the glomerulus in the Bowmans capsule
Extraglomerular cells are also known as modified mesangial cells AKA Lacis Cells and are located between the AA, EA, and DCT
